Enantioselective Organozinc Addition to Aldehydes Using Planar Chiral [2.2]Paracyclophane-Imidazoline N,O-Ligands.

We present an improved and convenient synthesis of [2.2]paracyclophane-imidazoline N,O-ligands with central and planar chirality in seven steps starting from [2.2]paracyclophane.

Zn(II)-catalyzed asymmetric [3 + 2] cycloaddition of acyclic enones with azomethine ylides.

The Zn(II)/UCD-Imphanol-catalyzed highly -selective [3 + 2] asymmetric cycloaddition of acyclic enones and azomethine ylides has been developed. Moderate to high yields (up to 94%) with excellent / selectivities (99 : 1) and enantioselectivities up to 96.5 : 3.

Zinc-Catalyzed Enantioselective [3+2] Cycloaddition of Azomethine Ylides Using Planar Chiral [2.2]Paracyclophane-Imidazoline N,O-ligands.

We present a facile synthetic route toward a novel series of imidazolinyl-[2.2]paracyclophanol (UCD-Imphanol) ligands possessing central and planar chirality. Both sets of diastereomeric ligands were successfully purified by column chromatography.

Catalytic asymmetric transformations of oxa- and azabicyclic alkenes.

Oxa- and azabicyclic alkenes can be readily activated by transition-metal complexes with facial selectivity, because of the intrinsic reactivity of strained bicyclic structures. Synthetically, these compounds are important synthons that offer an important platform for the construction of biologically/medicinally significant compounds with two or more stereocenters. This Review comprehensively compiles the diverse catalytic processes involving the enantioselective transformations of oxa- and azabicyclic alkenes.

Site-Selective Rh-Catalyzed C-7 and C-6 Dual C-H Functionalization of Indolines: Synthesis of Functionalized Pyrrolocarbazoles.

A site-selective dual C-7 and C-6 C-H functionalization of indolines with azabenzonorbornadienes has been accomplished using Rh-catalysis. The reaction affords a potential route toward pyrrolocarbazoles with broad scope and functional group tolerance.

Stereospecific Assembly of Fused Imidazolidines via Tandem Ring Opening/Oxidative Amination of Aziridines with Cyclic Secondary Amines Using Photoredox Catalysis.

Sustainable assembly of imidazolidines is accomplished via a sequential stereospecific ring opening and C-H amination using aziridines with secondary cyclic amines under visible light mediated indazoloquinoline photoredox catalysis at ambient conditions. Optically active aziridines are coupled with high enantiomeric purities. The computational studies provide insights on the redox properties of the catalysts as well as a profile of the reaction.

Synthesis of benzosuberone-tethered spirooxindoles: 1-3-dipolar cycloaddition of azomethine ylides and arylidene benzosuberones.

Expedient synthesis of benzosuberone-tethered spirooxindoles was accomplished by a three-component 1,3-dipolar cycloaddition reaction between azomethine ylide (generated in situ) and arylidene benzosuberone. This protocol offers good yield and wide functional group tolerance under mild reaction condition with high regio- and stereoselectivities.

Expedient stereospecific Co-catalyzed tandem C-N and C-O bond formation of N-methylanilines with styrene oxides.

Cobalt(ii)-catalyzed stereospecific coupling of N-methylanilines with styrene oxides is developed via tandem C-N and C-O bond formation using tert-butyl hydroperoxide (TBHP) as an oxidant. Optically active epoxide can be reacted with high optical purity.

A facile solvent-free three-component domino synthesis of novel 2,4-diaryl-5,6-dihydrobenzo[j][1,7]phenanthrolines.

A simple, efficient and green procedure for the synthesis of novel 2,4-diaryl-5,6-dihydrobenzo[j][1,7]phenanthrolines has been developed via a Krohnke-type one-pot three-component reaction of 2-[arylmethylidene]-3,4-dihydro-1(2H)-acridinones and (2-aryl-2-oxoethyl)pyridinium bromides in the presence of excess ammonium acetate in good yields under solvent-free conditions. Good functional group tolerance, high substrate scope and no column purification are the practical advantages of this methodology.

Copper(II)-Catalyzed Oxidative Coupling of Anilines, Methyl Arenes, and TMSN via C(sp/sp)-H Functionalization and C-N Bond Formation.

Copper(II)-catalyzed cross-coupling of anilines, methyl arenes, and TMSN in the presence of tert-butylhydroperoxide at moderate temperature produced 2-aryl benzimidazoles via a tandem C(sp/sp)-H functionalization and C-N bond formations. The selectivity and multiple C-H functionalization of the simple substrates are significant practical features.

A One-Pot Multicomponent 1,3-Dipolar Cycloaddition Strategy: Combinatorial Synthesis of Dihydrothiophenone-Engrafted Dispiro Hybrid Heterocycles.

The combinatorial syntheses of a library of novel dihydrothiophenone-engrafted dispiro oxindole/indenoquinoxaline-pyrrolidine/pyrrolothiazole/indolizine hybrid heterocycles have been realized through a chemo-, regio-, and stereoselective multicomponent 1,3-dipolar cycloaddition strategy.

A facile stereoselective synthesis of dispiro-indeno pyrrolidine/pyrrolothiazole-thiochroman hybrids and evaluation of their antimycobacterial, anticancer and AchE inhibitory activities.

A facile stereoselective synthesis of novel dispiro indeno pyrrolidine/pyrrolothiazole-thiochroman hybrids has been achieved by 1,3-dipolar cycloaddition of azomethine ylides, generated in situ from ninhydrin and sarcosine/thiaproline, on a series of 3-benzylidenethiochroman-4-ones. The synthesised compounds were screened for their antimycobacterial, anticancer and AchE inhibition activities. Compound 4l (IC 1.

One-Pot Access to a Library of Dispiro Oxindole-pyrrolidine/pyrrolothiazole-thiochromane Hybrids via Three-Component 1,3-Dipolar Cycloaddition Reactions.

A library of novel dispiro compounds containing oxindole pyrrolidine/oxindolopyrrolothiazole-thiochroman-4-one hybrid frameworks has been synthesized in a fully regio- and stereoselective fashion by the three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the condensation of isatins and secondary amino acids (sarcosine/l-thioproline) with 3-arylidenethiochroman-4-ones. This experimentally simple protocol provides good yields of structurally complex, biologically relevant heterocycles in a single operation.

An efficient synthesis of N-substituted 3-nitrothiophen-2-amines.

A novel protocol for the synthesis of 3-nitro-N-aryl/alkylthiophen-2-amines in good yields from the reaction of α-nitroketene N,S-aryl/alkylaminoacetals and 1,4-dithiane-2,5-diol in the presence of K2CO3 in refluxing ethanol is described. This transformation generates two C-C bonds in a single operation and presumably proceeds through a reaction sequence comprising 2-mercaptoacetaldehyde generation, nucleophilic carbonyl addition, annelation and elimination steps.

Synthesis of novel 16-spiro steroids: 7-(Aryl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazolo estrone hybrid heterocycles.

The 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the reaction of isatins or acenaphthylene-1,2-dione and 1,3-thiazolane-4-carboxylic acid to various exocyclic dipolarophiles synthesized from estrone afforded a library of novel C-16 spiro oxindole or acenaphthylene-1-one - 7-(aryl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazole - estrone hybrid heterocycles. These reactions occur regio- and stereo-selectively affording a single isomer of the spiro estrones in excellent yields with the formation of two C-C and one C-N bonds along with the generation of four new contiguous stereo-centers in a single step.